Agriculture Reference
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Table 4. Average distribution of different potassium salts in the crystals obtained from
neutralisation of Vinasseash[Sheehan and Greenfield, 1980]
Range (%)
Potassium sulphate, K 2 SO 4
66 - 68
Potassium chloride, KCl
16 - 17
Potassium carbonate, K 2 CO 3 .2H 2 O
6 - 7
Total potash as K 2 O
50 - 51
Total average potassium salts as %age of crystals
90
Zajic (1971) proposed deep well disposal of vinasse as a cheaper alternative. However
limited underground storage and specific geological formation preclude a wide scale stillage
disposal by this method [Sheehan and Greenfield, 1980]. Montanani (1954) described a
system in which stillage is neutralized with lime and evaporated to be used as a fertilizer.
Dubey (1974) discussed stillage disposal with particular reference to UK where 1280 m 3 of
stillage per hectare per year is required. The land is ploughed or sprinkled to control odour.
Sastry et al. (1964) however concluded that the process is not economical if odour is a series
issue.
Van Haandel (2005) discussed the feasibility of anaerobic digestion of sugarcane vinasse.
The anaerobic digestion of vinasse has been applied at full scale at several distilleries [Souza,
1992] with conversion efficiencies of more than 80% at organic loading rates of over 20kg
COD/m 3 /d. For the amount of COD in vinasse, about 100 kg of methane is produced at 80%
removal efficiency. If methane is used for power generation, 500kWh of power can be
produced for a generation efficiency of 35 - 40% [Van Haandal, 2005]. However, according
to Cortez and Perez (1997) economics associated with technical problems act as a limiting
factor for methane gas production by anaerobic fermentation of vinasse.
Julsingha (1970) described a process for removing potassium from vinasse. Vinasse was
concentrated to 30 - 60 ° Brix and H 2 SO 4 was added to it. Potassium was removed in the form
of K 2 SO 4 .5CaSO 4 .H 2 O. Reich (1945) proposed a system in which concentrated stillage is
passed through three low temperature carbonising retorts and activated at 870 °C. The
resultant carbon then undergoes counter-current aqueous extraction to produce potash liquor
and char. The liquor contains KCl and K 2 SO 4 for fertilizer use. Yamauchi, et al. (1977) burnt
stillage containing 21% solids using heavy fuel oil. Ash was dried to produce non-
hygroscopic granules to be used as a fertilizer. Sastry et al. (1964) reported 34.7% K 2 O and
2.2% P 2 O 5 in the stillage incineration ash. However, according to Monteiro (1975)
incineration to produce fertilizer is not economical.
Polack et al. (1981) showed that combustion of Louisiana‟s vinasse is very difficult and
they were not successful in the combustion of vinasse even when air was preheated and
different air fuel ratios were tested. However, Cortez and Perez (1997) were successful in
combusting vinasse alone in different solid concentrations and in co-firing 45° Brix as an
emulsion with #6 fuel oil. Vinasse used for the tests was from Shepherd oil distillery and its
composition is given in Table 5. They determined that the adiabatic flame temperature of
50% solids vinasse was 700 °C and that of 60% solids vinasse was 793 °C.
They combusted vinasse and #6 fuel oil emulsion in different concentrations and
concluded that the combustion of the emulsion was feasible when vinasse concentration in the
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